Hi i recently purchased the mkturbo kit from lars and i am having issues with getting the ecu to work all the time. it is a MS3X that he source for me because diyautotune does not have them available for 96-97 miatas at this time. I installed the ecu and wired in the power ground and AEM wideband as per the labelled wires. The first day having the ecu in i did not drive it at all and just had it sitting in the shop getting the idle afrs correct, the second day i took it on a drive about 90 minutes total and everything went smoothly (was using ve analyze live). The next morning it took about 10 tries of cranking before the car would start but being a cold start this was to be expected for the first real cold start (so i thought), parked it and at lunch time went out to the car it would crank but not start wouldnt even attempt to fire. later in the day i went out and tried to start it and it fired up within 3 engine revolutions. installed the mk intercooler kit that evening afterwards to pull the car back out of the shop it started and idled for 15 seconds then just shut off, hooked laptop up to because i had it with me at this time for and im getting an "offline" message with the key on and connected to the laptop. i checked for power and grounds going to the ecu has good power and ground, i then restarted megasquirt and started a new project still with the ecu connected to the laptop with key on and it picked up the ecu and i could hear relays turn on and then the car would start, then drove around a little, everything seemed fine until i went to drive it the next day and it wouldnt start again. going through and looking at all the possible causes that could be me i checked the 12v key signal wire for power it has good power, decided maybe the source i had it tapped into had a resistance causing low current i found that with key on and this wire not connected to the power source it still is getting 12v. my real question with all of this is it an ecu issue or is there something that im missing with this whole thing? there was only 3 wires with my whole jumper harness that were not connected to anything and that was ecu ground which i installed to the same location as wideband a key on power signal wire which i tapped directly to the fuse box under the dash and a wideband signal wire. Note when the ecu decides to turn on and work all functions seem to be normal afrs match gauge, fuel pressure air and coolant temps, adjusting fuel maps, everything appears to be in working order just the ecu seems to not want to turn on. Thanks in advance if anyone can help.

 

What exactly is your problem? Cold starts take a minute?

 

First things first. Break that giant thing of text up so it is actually readable and have your specific questions easy to find.
Post your current tune file and even a data log would be hugely helpful.

Once we have that we can start to help. Sounds like a user issue in either how you wired it or how you are tuning it.

 

^This. It's hard to follow along a story about your issues.

From what I could follow, this sounds like a wiring issue more than anything. There's no reason you should ever have to make a new project (unless something got corrupt, which would likely be due to wiring issues). The fact that the new project worked probably means that either something was corrupt, or the wiring fixed itself in the time you took to make a new project (grounds can be finicky like that).

 

For whatever reason, if I close my laptop w/ Tuner Studio open and come back the next day to change something on MS it will stay offline until I close TS and reopen my old project. Sounds like that is most likely drivers or just a natural flaw of Tuner Studio and some laptops. Whatever the cause, my solution is to just close TS every time I'm done with it, and open up a fresh one before tuning.

 

The next morning it took about 10 tries of cranking before the car would start

The above is also a tuning issue you have. Mine starts after about 4s of cranking when cold and im still not happy with that.

 

I'm not a tuner or that smart in this field but.. cranking pw?

 

There are a few things ill be adjusting to get mine to start as quick as im happy with but we can discuss that in my build thread, no need to clutter up this guys thread on un-necessary gobbledygook.

 

Sorry for the big mess of a story (only use on mobile so format usually looks ok to me). My concern is that it will be working fine then the next time I go to start it, it acts as if the ecu will not power on. I'm not sure if if it's how I'm shutting down tuner studio, but it appears like the ecu gets stuck in off position. It had good cold starts in -15 weather. During the cold starting there was no audible attempt at it firing or injecting fuel. I had started it and drove it for 20 mins and parked then it shut itself off (I don't remember if I had shut down tuner studio first or not here). It's running the base tune from braineak all I've done is adjust the fuel map so it won't go lean. And I've installed the iat/wideband and calibrated sensors as per trubokitty guide.
1 Is it possible to "lock out" the ecu if I close out tuner studio with it still running?
2 is it possible whatever issue (power, ground or signal) I had during that cold start cranking fixed itself?
3 how come the 12v key on signal I'm supposed to wire in would have 12v coming from the ecu when it's not connected on the car side?
4 why would my laptop see it as offline all the time?

 

1. No, the ECU would just run with the latest burn or map update
2. Yes, vibration, heat, etc will moves things and intermittent wiring issues can be fixed/caused with very minor inputs
3. Please elaborate. Where are you measuring 12V from? So the ECU is unplugged completely and the ECU has 12V? That's not possible.
4. ECU doesn't have power, bad connection internal to the ECU, bad/missing drivers on the laptop, failing USB cable

 

My ecu came with 3 wires needing to be installed by me. Black for ground, pink I believe for wideband signal and a red one that was labeled 12v sig. assuming the red one was supposed to be wired to a 12v key on source. I cut this wire from where I had wired it in. key off this wire was ground key on this wire turned to 12v power with it still disconnected from the car source. My serial - USB is a brand new cable came with its own driver software which I installed and had it functioning perfect. The ecu will be offline according to the laptop at the same time it's not starting (will crank but doesn't attempt to fire). but when the ecu appears to be working fine the laptop connects no problem. Note: plugging the USB cable in and out of the laptop it recognizes something is being plugged in and out.

 

Give us all the details. Maybe some pictures. So the ECU is an MS3x and has a jumper harness with 3 of the wires not going anywhere? "I cut this wire from where I had wired it in." - Where did you have it wired to? "key off this wire was ground key on this wire turned to 12v power with it still disconnected from the car source" - punctuation goes a long way to help understand. If I understand correctly, if the rest of the harness is connected but the power wire isn't. The ECU can be back fed with 12V, I'm guessing over the solenoids or something. This is a very weak power source (since it's not direct 12V into the ECU) and will get pulled very low during cranking. My friend had the same issue, he didn't wire the power wire correctly, but he thought he was fine since there was 12V on the input. It would get pulled down to like 6 or 7V during cranking and kill the connection. We found that the power wire wasn't getting 12V from the vehicle and that "12V" was back fed from inside the ECU. Wired it properly and it was fine.


If it won't connect and doesn't show signs of combustion while cranking, the ECU likely doesn't have power.

 

You understood exactly. I had the 12v signal tied in with radio 12v signal. I tried jumping that signal wire direct from battery with key on to try and get it to turn on, No reaction from ecu or from laptop. I made sure there was enough current flow going through signal wire (prior to disconnecting) to light up a test light ( incandescent bulb not led)

 

I was told by Lars yesterday, that this ecu was built by brain. sorry I can't get pictures of it until tomorrow I've been out of town since Friday.

 

I think I found something that might be an issue. This picture of the 12v switched power is soldered to a brown/red wire labelled can low. To me it wouldn't make sense to have these 2 soldered together. any insight to the issue would be much appreciated. Now with this being directly powered could this cause any circuit board issues? (Haven't removed the case to inspect the board yet) is there any way I can tag braineak and shuiend in this?

 

A convenient coincidence for you: I happen to have the same ECU and same car as you, and I emailed to confirm the purpose of those wires yesterday, here was the response:

I don't think you want that tan/red wire hooked up to switched 12v, as it is intended to provide 12v power to the wideband.

EDIT: Realized my last sentence is a bit confusing. I mean you wouldn't want that brown/red wire hooked up to your radio 12v power wire. It being soldered to the adjacent red wire at the DB37 connector appears intentional such that it can provide power to the wideband.

 

wait, where did you attach that black wire? to voltage?

the red wire is the power source for a wbo2, the black wire is a ground source for a wbo2, and the pink wire is the wbo2 input.

 

Black wire I hooked to ground with the wideband. red wire I hooked to a switched 12v not really realizing it was putting 12v out so no harm there. pink wire I used for my wideband input signal

 

you mean like you don't even hear the starter?

 

The starter cranks just fine every time I turn the key. But there's no sound of it igniting or injecting fuel. While cranking the wideband works and it'll pin at 19 as no fuel is being injected. While Attempting communication with laptop it won't change from "not connected". I have the ecu currently sitting on my table tried using the printer cable and serial cable to power it up (without the db37 connectors) and it still says "not connected"